What is "QApplication app(argc, argv)" trying to do?

Question

#include <QtGui/QApplication>
#include <QtDeclarative>
#include "qmlapplicationviewer.h"

int main(int argc, char **argv) {
    QApplication app(argc, argv);
    QmlApplicationViewer viewer;

    viewer.setMainQmlFile("app/native/assets/main.qml");
    viewer.showFullScreen();

    return app.exec();
}

My C++ is a bit rusty. Can someone please explain to me what is "QApplication app(argc, argv)" trying to do ?

Is it trying to declare a function which takes in 2 arguments (argc and argv) and return a variable of type QApplication ?

Answer 1

The line

QApplication app(argc, argv);

creates a new instance of type QApplication and invokes the constructor of this class. In your example, the variable app now stores this instance. It is somewhat (semantically) a shorthand of this:

QApplication app = QApplication(argc, argv);